The use of surgical fixation plates for a variety of orthopaedic applications is a widely accepted. Fixation plates are used by surgeons to stabilize, mend, or align fractured or diseased bones as well as to apply compression or tension to bones and to fuse joints between two or more bones. Typically, fixation plates are fastened to the bone with at least one, and often a plurality, of fasteners such as bone screws that are installed through bone screw holes in the plate. Proper orientation and alignment of the fasteners with the bone plate and secure fixation of the bone plate to the bone can mitigate potential complications after implantation.
Fixation plates used in spinal applications must be installed with special care. The margin for error in spinal surgery is small, particularly because of the sensitivity of the spinal cord and the risk inherent in performing invasive procedures near the spinal cord. Furthermore, the dimensions of vertebral bone available for receiving fasteners are fairly constrained.
Screws used to secure the bone plate often must be precisely aligned to facilitate retention of the fasteners in the bone. In some instances the fasteners may be particularly aligned in order facilitate compression between opposing bone segments. Misalignment of the screw within the screw hole of the plate may increase the risk of tissue damage, bone screw failure, fixation failure, and/or bone screw ‘back-out’ thus increasing the risk of further injury to the patient and defeating the usefulness of the plate. Locking plates in particular demand the aforementioned precise fastener alignment for proper function.
Drill guides are often used to facilitate the alignment of bone screw pilot holes and the insertion of bone screws. A typical drill guide attaches or abuts against an associated fixation plate and includes a guide tube for guiding surgical tools (e.g. awls, taps, drills, screws and screwdrivers) toward and through the bone screw hole in the plate. One drawback of the typical drill guide is that it is yet another piece of surgical equipment that must be separately manipulated and accounted for at the surgical suite. A surgeon must manipulate both the tool that is inserted through the drill guide and the drill guide itself, or must have assistance in doing so. This often complicates the surgical procedure, increases the chance for error, and increases the length of surgical procedure.
Traditional drill guides have included depth limiting arrangements of different sorts for limiting the penetration depth of drills, awls, taps, and other similar bone piercing and boring tools. Currently, there are generally two methods of limiting drilling depth. One consists of an adjustable drill guide that is typically a tubular member with a handle, where the tubular member receives drilling tools therethrough. The tube typically has a stop mechanism that engages with the drilling tool, such as opposing surfaces on the drill guide and on the drill bit that come in contact. Often, one of the components surfaces is adjustable by a threaded mechanism or the like, such that the penetration depth of the component can be adjusted. Another traditional mechanism is a tubular drill guide having a single stop that interacts with different drill bits, where each drill bit has a stop at a different location according to a preferred drilling depth.
Providing a surgeon with the ability to select a preferred drilling depth increases the efficiency and accuracy of many surgical procedures. This is because many different lengths of screw are used for different procedures and different patient anatomy's. Furthermore, the depth of a bone screw hole, and the length of a bone screw also depends on the bone quality into which the screw is to penetrate. Yet another consideration is the amount of injury that may result if the drilling procedure and or bone screw penetrate beyond a particular depth. For example, the injury that may result from a misplaced, mis-angled, or misjudged penetration depth of a bone screw placed into a vertebra often can be drastic and permanent.
Accordingly, a device and method for combining the beneficial functions of a drill guide and a depth limiting guide into a single surgical tool would be highly desirable.